Educational Codeforces Round 3

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本文探讨了使用多个不同容量的USB闪存盘存储文件的策略，并通过实例展示了如何优化存储需求。同时，介绍了为特定场合选择不同类别的礼物的算法，涉及书籍类型的选择和组合。

Sean is trying to save a large file to a USB flash drive. He has n USB flash drives with capacities equal to a1, a2, ..., an megabytes. The file size is equal to m megabytes.

Find the minimum number of USB flash drives needed to write Sean's file, if he can split the file between drives.

Input

The first line contains positive integer n (1 ≤ n ≤ 100) — the number of USB flash drives.

The second line contains positive integer m (1 ≤ m ≤ 105) — the size of Sean's file.

Each of the next n lines contains positive integer ai (1 ≤ ai ≤ 1000) — the sizes of USB flash drives in megabytes.

It is guaranteed that the answer exists, i. e. the sum of all ai is not less than m.

Output

Print the minimum number of USB flash drives to write Sean's file, if he can split the file between drives.

Sample test(s)

input
3
5
2
1
3

output
2

input
3
6
2
3
2

output
3

input
2
5
5
10

output
1

#include <bits/stdc++.h>

using namespace std;

int a[110];
int main()
{
    int n,m;
    while(~scanf("%d%d",&n,&m))
    {
        for(int i=0;i<n;i++)
        {
            scanf("%d",&a[i]);
        }
        sort(a,a+n,greater<int>());
        int sum = 0;
        int i;
        for(i=0;i<n;i++)
        {
            sum+=a[i];
            if(sum >= m)
                break;
        }
        printf("%d\n",i+1);
    }
    return 0;
}

Emily's birthday is next week and Jack has decided to buy a present for her. He knows she loves books so he goes to the local bookshop, where there are n books on sale from one of m genres.

In the bookshop, Jack decides to buy two books of different genres.

Based on the genre of books on sale in the shop, find the number of options available to Jack for choosing two books of different genres for Emily. Options are considered different if they differ in at least one book.

The books are given by indices of their genres. The genres are numbered from 1 to m.

Input

The first line contains two positive integers n and m (2 ≤ n ≤ 2·105, 2 ≤ m ≤ 10) — the number of books in the bookstore and the number of genres.

The second line contains a sequence a1, a2, ..., an, where ai (1 ≤ ai ≤ m) equals the genre of the i-th book.

It is guaranteed that for each genre there is at least one book of that genre.

Output

Print the only integer — the number of ways in which Jack can choose books.

It is guaranteed that the answer doesn't exceed the value 2·109.

Sample test(s)

input
4 3
2 1 3 1

output
5

input
7 4
4 2 3 1 2 4 3

output
18

#include <bits/stdc++.h>
using namespace std;
int h[11];
int main()
{
    int n,x,m;
    while(~scanf("%d%d",&n,&m))
    {
        memset(h,0,sizeof(h));
        for(int i=0; i<n; i++)
            scanf("%d",&x),h[x]++;
        int ans = 0;
        for(int i=1; i<10; i++)
            for(int j=i+1; j<=10; j++)
                ans += (h[i]*h[j]);
        printf("%d\n",ans);
    }
    return 0;
}